
where in the last step we used the Cauchy-Schwarz inequality. For the term \(\Vert x_t-z_t\Vert _{(t-1)}\)  we can apply [1]} with:
\(&\phi _1(x)=r_{0:t-1}(x) +c_{1:t-1}^\top x + \tilde{c}_t^\top x \\&\phi _2(x)=r_{0:t-1}(x) +c_{1:t-1}^\top x + \tilde{c}_t^\top x + ( c_t^\top x - \tilde{c}_t^\top x ) \\&\psi (x)=c_t^\top x - \tilde{c}_t^\top x\) 
